Mechanical pool cleaners which utilize the flow of water drawn through the cleaner by means of a connectable flexible suction pipe in communication with a filtration system pump are well known. Such pool cleaners are termed suction cleaners. Some suction cleaners interrupt the flow of the water induced through at least one passage through the cleaner to provide the propulsive force to move the cleaner in a random manner across the surface to be cleaned.
In U.S. Pat. No. 3,803,658 to Raubenheimer discloses a cleaning device which employs a water cut-off valve carried in rotational movement by a wheel driven by the flow of liquid through the cleaner. As is typical for a suction cleaner, a flexible hose leads from the suction chamber of the device to the suction side of the filtration system pump. When in use for cleaning a swimming pool, the hose becomes filled with water and the continuous opening and closing of the valve causes the hose to jerk. As the suction against the surface to be cleaned is momentarily released each time the gate closes, the jerking movement of the hose causes the head to move over the surface.
A water interruption pool cleaner developed by Chauvier and described in U.S. Pat. No. 4,023,227 uses the oscillatory movement of a flapper valve of substantially triangular cross-section displaceably located in the operating head of the cleaner and between two valve seats to alternately close off the flow of water drawn through a pair of passages in the cleaner which is connected by means of a suction pipe to the filtration system pump. The passages are located parallel to each other and are preferably oriented at an angle of 45.degree. from the surface to be cleaned. The sudden halt of the flow of liquid through one passage applies an impulsive force to the apparatus due to the kinetic energy of the fluid flowing in the passage. This impulsive force is sufficient to displace the pool cleaner along the surface to be cleaned. Further, due to the inertia of the liquid in the passage to which flow is transferred, the pressure differential between the low pressure in the head and the ambient pressure of the water surrounding the cleaner is temporarily reduced, thereby decreasing the frictional engagement between the head of the pool cleaner and the surface, allowing the cleaner to be displaced.
By way of further example, water interruption pool cleaners which are more compact than the Chauvier device described above are disclosed in U.S. Pat. Nos. 4,133,068 and 4,208,752 issued to Hofmann. They employ an oscillatable valve adapted to alternately close a pair of passages in the head of the cleaner. A baffle plate is disposed in the head between the inlet and valve to cause one of the passages to be more restricted and less direct between inlet and outlet.
U.S. Pat. Nos. 4,682,833 and 4,742,593 to Stoltz and Kallenbach respectively, achieve autonomous water interruption by providing an assembly including a tubular flow passage at least partly defined by a transversely contractible and expandable tubular diaphragm, the tubular flow passage and tubular diaphragm are enclosed within a chamber formed by the body of the cleaner. The assembly includes means whereby pressures internally of the tubular diaphragm member and externally of tubular diaphragm member within the chamber formed around the member by the body are controlled so that, in use with fluid flowing through the diaphragm, it will be caused to automatically and repeatedly contract and expand. A pulsating flow of fluid through the assembly results and in forces cause the displacement of the pool cleaner apparatus over a surface to be cleaned.
To effect interruption of an induced flow through a swimming pool cleaner, U.S. Pat. No. 4,807,318 to Kallenbach discloses a tubular axially resilient diaphragm located within a chamber. One end of the diaphragm is closed and adapted to hold normally closed a rigid passage from the head of the pool cleaner to the usual form of suction pipe which connects the pool cleaner to the filtration unit. The diaphragm and its closed end also provide means for subjecting the interior of the diaphragm to variations in the pressure of water flow through the cleaner during use.
U.S. Pat. No. 4,769,867 to Stoltz describes a water interruption pool cleaner having a passage there through from an inlet end to an outlet in communication with a suction source. A valve in the form of jaw-like members is located at the fluid intake end of a rigid tubular section within a passage of the cleaner. In response to an induced flow of water through the valve and the tubular section, the jaw-like members automatically move relative to each other about an axis transverse to the length of and adjacent the end of the tubular section. The members are tapered towards each other to an inlet between them at their free ends with flexible membranes located between the sides of the jaws.
In another pool cleaner invention described in U.S. Pat. No. 4,817,225 to Stoltz, water interruption is achieved by means of a spherical closure member which is free to move in the head of the cleaner towards and away from a closure valve seat located at the upstream end of the outlet from the head. A hollow axially contractible resilient member is connected to the outlet at one end with its other end is connected to a flexible suction pipe.
U.S. Pat. No. 5,404,607 to Sebor for a Self Propelled Submersible Suction Cleaner uses an oscillator pivotally mounted within the flow path of a suction chamber to cause abrupt changes in water flow and thereby impart vibratory motion to the housing. Shoe means incorporating angled tread elements cooperate to move the housing along a forwardly direction of travel in response to the vibratory motion. Means are provided for converting a reciprocal angular movement or to and fro movement of the oscillator to an angular movement in one direction for purposes of driving a shaft. To enable the Sebor '607 cleaner to turn at established intervals throughout its travel over the surface to be cleaned, a drive gear is affixed to the shaft and engages a gear train which, in turn, engages a rotatable coupling at defined intervals to generate rotation of the coupling at these defined intervals. When in use, the rotatable coupling is connected to a flexible suction hose in communication with a filtration system pump.
Typically, a flapper valve used in such devices emit a hammering sound which can be irritating to a user. By way of example, if the swimming pool is located close to a building, the sound may resonate through the structure and be audible inside the rooms. Many devices known in the art are large and cumbersome. This impairs its maneuverability and effectiveness in smaller-sized pools and those where the transitions between the walls and/or between the floor and walls are sharp or tight. Debris such as twigs, berries and stones may become trapped in the operating head between the flapper valve and the valve seats. In order to clear debris or perform other maintenance tasks, it is difficult to gain access to the valve chamber, the flapper valve, valve seats and the openings in communication with the passages.
Sticks and larger pieces of debris may damage or puncture the flexible tubular member or may become entrapped in the members. Access to and removal of the flexible tubular member which is enclosed within a chamber is difficult and typically a non-technical person will avoid attempting easy repair. Replacement of the member may require tools which a typical homeowner may not have or be comfortable using. Often times, the pool cleaner provides a strong suction for effectively moving over the surface to be cleaned, but to its detriment fails to create a suction flow through the cleaner sufficient to remove sand located on the surface to be cleaned.